Last year I cut that first plant all the way down to where the first branches started. I mean all the way down to just a nub.
I used some of the cuttings to line the rest of that bed. I rooted them in water then transplanted them into cups and then later into the ground. I passed on all the rest of 'em at the spring swap.

That front plant looked like all those others behind it do now, all scraggily and split open. But now its full and twice the size. It is full and shaped well. I'm going cut all the rest of 'em back and down, hoping they'll fill back in like this first one did.

Here is what last years cuttings look like now, and also what that first one in the above picture looked like this time last year. During the summer they all looked a lot better than they do now. See the light green? Thats new growth, its going to fill in all that dead space before the cannas even break ground. I'll cut back everything except that new light green stuff.

During the summer there are huge red cannas behind the artimesia. It gets afternoon sun there.